The present invention principally relates to a new building drainage system.
A conventional building drainage system used for apartment houses, detached houses, etc. generally includes a drainage stack (hereinafter, referred to as xe2x80x9cstackxe2x80x9d) passing through stories; appliance drainage pipes (hereinafter, referred to as xe2x80x9cdrainage pipesxe2x80x9d) connected to water-service terminal appliances such as a kitchen and a basin provided on each of the stories and extending while being tilted at a slight slope with respect to a floor slab of the story; and a combined joint (hereinafter, referred to as xe2x80x9cjointxe2x80x9d) for connecting the drainage pipes on each story to the stack, the joint being provided on the same story; wherein waste water from the water-service terminal appliances on each story is discharged in the drainage pipes, being introduced to the joint provided on the same story, and is combined to a fluid flowing in the stack. At the joint of such a conventional drainage system, the drainage pipes cross the stack at an angle of 90xc2x0 or slightly smaller than 90xc2x0, and therefore, the joint is required to have a large capacity, particularly, a large horizontal cross-section. As a result, there arise problems that the joint becomes heavy and expensive, and further becomes poor in the degree of freedom in design because the joint requires a wide space.
In other words, the vertical velocity component of a fluid flowing in each of the drainage pipes is significantly low, and accordingly, at the joint for connecting the drainage pipes to the stack, a cross-sectional occupancy of the fluid in the drainage pipes to a fluid in the stack becomes very large. As a result, a ventilation resistance caused when the fluid flowing in the drainage pipes is combined to the fluid flowing down in the stack becomes significantly large. For this reason, when combined with the fluid flowing down in the stack, the fluid flowing in the drainage pipes interferes with the fluid flowing in the stack, to increase the negative pressure in the stack, thereby causing breakage of sealing of a trap and abnormal noise.
A combined joint configured such that drainage pipes are connected to a stack while being tilted at a specific angle with respect to the stack has been disclosed; however, such a joint is intended to obliquely combine a fluid flowing in each drainage pipe to a fluid flowing in the stack. To be more specific, according to this joint, since the vertical velocity component of the fluid flowing in the drainage pipe is low, there arises the same problem as that described above.
Such a problem is basically due to the fact that the vertical velocity component of a fluid or waste water transversely flowing from appliances on each story is, at the combined joint provided at the same story, largely different from a vertical velocity of a fluid flowing down in the stack passing through the stories, to cause a negative pressure, thereby causing breakage of sealing of a trap and abnormal noise. To solve such a problem, the joint is required to be enlarged, resulting in the raised manufacturing cost. Also if there occurs breakage of sealing of a trap or the like, the sanitary function of the drainage system is lost. To avoid such an inconvenience, the maintenance for the drainage system must be frequently performed, which results in the raised maintenance cost.
A special drainage joint represented by a Solvent drainage system has been known. This joint is intended to make small the cause of generation of a negative pressure by largely expanding the horizontal cross-section of a combined portion and a connecting portion of a stack is offset. Such a joint, however, is large in size and weight, so that the manufacturing cost thereof is increased.
In general, according to the conventional building drainage system, waste water from a water-service terminal appliance is combined to that from another appliance at the same level, and is carried in a drain pipe with a slope in an open-channel manner, that is, in the state in which the drain pipe is not fully filled with the waste water. As a result, the drain pipe is required to be sufficiently thick and to have a standard slope, thereby causing a problem in giving a limitation to the degree of freedom in building plan.
According to the conventional building drainage system, even if there occurs clogging of a drain pipe or leakage of water from a deteriorated drain pipe, such a drain pipe cannot be repaired unless the interior of the building is partially broken, and the replacement of the drain pipe with a new drain pipe requires interruption of the use of the drain system and also requires a large cost. Further, according to the conventional building drainage system, since various kinds of waste water given to an environment by human activity are immediately combined to each other, there occurs a problem in which it is difficult to realize water-saving and make effective use of resources by recycle of heat and organic matters.
An object of the present invention is to provide a new building drainage system capable of improving the problem of the prior art system, particularly, reducing the so-called ventilation resistance by press-feeding a fluid in each drainage pipe under a siphon phenomenon, thereby allowing the fluid to flow in the drainage pipe in a full-channel manner, that is, in a state in which the drainage pipe is fully filled with the fluid.
To achieve the above object, according to the present invention, there Is provided a building drainage system including: a drainage stack passing through stories in the vertical direction; appliance drainage pipes connected to water-service terminal appliances on each of the stories, each of the appliance drainage pipes including a transversely extending portion and a downwardly extending portion; and a combined joint for connecting the appliance drainage pipes provided on each of the stories to the drainage stack; wherein the combined joint for connecting the appliance drainage pipes provided on each of the stories to the drainage stack is at a level lower than that of a floor slab of the story, to sufficiently give a vertical velocity component to a fluid flowing in each of the appliance drainage pipes, thereby combining the fluid to a fluid flowing in the drainage stack.
Preferably, each of the appliance drain pipes has a transversely extending portion and a downwardly extending portion, and the combined joint is disposed at a level lower than that of the transversely extending portion of the appliance drain pipe by a specific distance. The specific distance may be in a range of 100 cm or more, preferably, 200 cm or more; or may be equivalent to the vertical length of one story of an apartment house or the like.
Preferably, each of the appliance drainage pipes is connected to the combined joint while being tilted at a specific angle with respect to the vertical line. The specific angle may be in a range of less than 45xc2x0 preferably, less than 30xc2x0, more preferably, less than 15xc2x0. Most preferably, each of the appliance drainage pipes is vertically connected to the combined joint.
The appliance drainage pipes may be singly connected to the combined joint. Also, the appliance drainage pipes may have the same diameter. Further, each of the appliance drainage pipes may be a flexible resin pipe.
The transversely extending portions of the appliance drainage pipes on each of the stories are placed on the floor slab of the story with no slope. Further, a portion, to be connected to the drainage stack, of each of the appliance drainage pipes may be provided with a counter-flow preventive valve having a flow control function.
According to the building drainage system having the above configuration, various kinds of waste water from water-service terminal appliances are discharged to the independent drainage pipes each having the transversely extending portion and the downwardly extending portion, being increased in vertical velocity component during a period of flowing down in the downwardly extending portions of the drainage pipes, and are combined to a fluid flowing in the stack. Accordingly, it is possible to significantly reduce the so-called ventilation resistance, and hence to make a negative pressure in the stack significantly smaller than that in the conventional building drainage system. Further, since the fluid flows in the drainage pipe in a full-channel manner under the siphon phenomenon, it is possible to make thin the diameter of the drainage pipe, and to eliminate the need of sloping the drainage pipe toward the stack. Even in the case of using a drainage pipe with a slight inverse-slope, the drainage can be sufficiently performed.
The present invention will be more concretely described below. The flexible pipes (drainage pipes) singly connected to appliances on each story are arranged such that the transversely extending portions of the pipes are placed on the floor slab of the story and the downwardly extending portions of the pipes are connected to the joint disposed at a level lower than that of the story. That is to say, the flexible pipe extends in the horizontal direction until it reaches the stack, being bent therefrom, and extends in the vertical direction, so that the fluid flows in the flexible pipe in a full-channel manner at a high velocity, and is combined to the fluid in the stack. To be more specific, the vertical velocity component of the fluid in the flexible pipe becomes at least 100 times that of the fluid flowing in the conventional drainage pipe, and a ratio of the vertical velocity component of the fluid in the flexible pipe to the final vertical velocity component of the fluid in the stack becomes about 0.3 to 0.5. Accordingly, as compared with the vertical velocity component of the fluid flowing in the drainage pipe (with a slope of {fraction (1/1000)}) of the conventional building drainage system, the cross-sectional occupancy of the fluid in the drainage pipe to the fluid in the stack becomes smaller, so that the ventilation resistance at the combined joint is significantly reduced by combination of the effect of reducing the flow rate of waste water by use of the drainage pipe having a small diameter, to suppress occurrence of a negative pressure in the stack, thereby improving the conventional building drainage system.
Assuming that the allowable flow rate of a fluid in the stack is nearly constant, the size of the joint of the present invention can be made smaller than that of the conventional joint. This allows the compact design of the drainage system. On the contrary, if the size of the joint of the present invention is designed to be identical to that of the conventional joint, it is possible to obtain a large allowable flow rate of the fluid in the stack.
Since the drainage pipes are basically configured as independent flexible pipes, the capacity of each drainage pipe is not required to be made large. For example, the drainage pipe may be configured as the polybutene pipe having a diameter of 20 mm. Further, since these pipes identical to each other in material and size are connected to respective appliances, it is possible to simplify the works of mounting the pipes.
Since the diameter of the drainage pipe of the present invention is reduced, the flow rate of waste water in the drainage pipe becomes about xc2xd to xc2xc the flow rate of waste water flowing in the conventional drainage pipe. Further, since the vertical velocity component of the waste water flowing in the downwardly extending portion of the drainage pipe is increased to a value of about 2-2.5 m/sec, the waste water is combined to a fluid in the stack at a high velocity. Accordingly, it is possible to suppress the increase in ventilation resistance at the joint and relieve a negative pressure in the stack even in the case of using the joint having a small capacity.
The conventional drainage system has the following problem: namely, when the drainage of waste water flowing in a drainage pipe connected to an appliance in a full-channel manner is completed, air is strongly sucked from the drainage port of the appliance through the drainage pipe by a siphon suction force; and such air interferes with the waste water remaining in the drainage pipe, to cause large suction noise. The building drainage system of the present invention is also improved to solve the problem associated with noise caused by suction of air upon drainage.
In this way, according to the present invention, since the drainage pipes from appliances are independent from each other, it is possible to increase the degree of freedom in design upon enlargement or repair of the building. Also, by use of the drainage pipes having the same diameter, it is possible to simplify the works of mounting the drainage pipes. Further, the transversely extending portion of the drainage pipe can be arranged to extend toward the stack with no slope.
The leading end, to be combined to the stack, of the drainage pipe is preferably provided with a valve having both a flow control function and a counter-flow preventive function. For example, the valve may be configured to be opened at a water pressure of 2 mAq and to be closed after completion of drainage. The use of such a valve allows a cyclic siphon drainage of waste water in the drainage pipe, which enables the automatic cleaning of the inside of the drainage pipe.
To be more specific, upon completion of drainage of waste water in the drainage pipe at a water-filling ratio near the full-filling ratio or upon induction of the siphon phenomenon by washing-and-draining, if the amount of waste water is small, atmospheric air is sucked from the drainage port of the appliance and thereby the flow of the waste water is temporarily stopped. At this time, there occurs large drainage noise. To prevent occurrence of such noise, it may be desirable to provide a drainage valve having a flow control function capable of adjusting the siphon suction force, and automatically changing the opening degree in proportional to the magnitude of a static pressure generated by the fluid in the drainage pipe.
The drainage pipes basically, singly extend to the combined joint, and in some cases, the drainage pipes may be bundled before being connected to the joint. These drainage pipes are generally directed around the stack, and in some cases, the drainage pipes can be collected and housed in a ventilation stack passing through an apartment house in the vertical direction.
A polybutene pipe can be widely adopted as the flexible resin pipe as the drainage pipe. A method of connecting the polybutene pipe to the joint with a single-motion has been developed. For the drainage system of the present invention, it may be desirable to adopt such a connection method for connecting the polybutene pipe to the joint.